An inkjet recording method is a recording method for forming an image by providing small ink droplets to a recording medium such as plain paper and a glossy medium, and has become rapidly widespread due to price reduction and improvement of a recording speed. Further, in addition to advanced high-definition of an image obtained by the inkjet recording method, along with rapid spread of digital cameras, the method has become widely common as an output method of images comparable to a silver halide photograph.
Examples of the problem of the ink jet recording method include deterioration in image fastness of the recorded material obtained. In general, the recorded matter obtained by the inkjet recording method has low image fastness as compared to a silver halide photograph. Specifically, when the recorded material is exposed to water, light, humidity, heat, environmental gases present in the air or the like for a long period of time, there is a problem in that a color material on the recorded material is apt to deteriorate to cause a change in color tone or color fading of the image.
In forming a color image, an ink set in which ink compositions with a plurality of colors are combined with each other is used. In the ink set, when image fastness of a specific ink composition, such as light resistance or ozone resistance is significantly lower than those of the other ink compositions, a color formed by the specific ink composition is faded or discolored more rapidly than the other colors, and thus the color tone balance of the entire color image deteriorates. Therefore, it is preferred that the image fastness of each ink composition constituting the ink set is excellent and a difference in image fastness between the respective ink compositions is small.
Among yellow, magenta, and cyan inks widely used as ink for inkjet, magenta, particularly, light resistance of the image of yellow ink tends to be inferior to those of images of the other ink. As a colorant used in the yellow ink, various azo compounds are known.
With respect to such problems, various yellow inks color tones of which are good and which are aimed to improve fastness to light, wet heat, and gas such as ozone have been proposed (see Patent Documents 1 and 2).